This invention generally relates to a water pump mechanism. More particularly, the present invention pertains to a water pump which is used for a vehicle.
A known water pump for a vehicle use is disclosed in U.S. Pat. No. 4,966,572. This known water pump, as shown in FIG. 4, includes an impeller 41 and a pulley 42, and the pulley 42 is press-fitted to a shaft which rotates integrally with the impeller 41, and the pulley 42 rotates by receiving the torque from outside. An outer ring of a bearing 43 is fitted to an inner ring of the pulley 42 which is press-formed with a steel plate, and a body 44 which is fitted in an inner periphery of the bearing 43 is supporting the pulley 42 through the bearing 43. According to a required specification of an engine to which a water pump is assembled, a diameter of a pulley, which receives torque for driving a water pump, needs to be changed. However, because the known water pump is structured with the outer ring of the bearing 43 fitted to an inner surface of the pulley 42, and the body 44 supports the pulley 42 through the bearing 43, an outer diameter of the pulley 42 is not so different from an outer diameter of the bearing 43. Therefore, the designing choice of the diameter of the pulley is limited.
Also, as a problem of a press-formed pulley, if a thick steel plate is press-formed to secure strength of the pulley, it is assumed that formation becomes difficult and a dimensional accuracy (cylindricality or vibration etc) of the press-formed pulley is reduced. On the other hand, if a thin steel plate is used for simplifying the formation process and improving the dimensional accuracy after formation, the strength of the pulley may decrease, and when the pulley is fitted to a bearing, the pulley may be deformed, impairing the dimensional accuracy (cylindricality or vibration, etc.), or the fitting strength between the pulley and the bearing may decrease.
According to one aspect of the invention, a water pump includes a driven portion, a shaft which is connected to the driven portion, an impeller which is connected to the shaft, a body which supports the driven portion for relative rotation therewith through a bearing, characterized in that an outer surface of the bearing is fixed together with the driven portion, and the driven portion and the shaft are formed integrally by resin molding.
According to this aspect, a driving force, which is inputted to the driven portion, rotates the impeller through the shaft, which is integrally formed with the driven portion.
According to another aspect of the invention, the water pump includes the driven portion, the shaft which is connected to the driven portion, the impeller which is connected to the shaft, the body which supports the driven portion for relative rotation therewith through the bearing, characterized in that the outer surface of the bearing is fixed together with the driven portion, the driven portion is comprised of a pulley portion and an arm portion, the pulley portion is fixed to the arm portion, and the arm portion is fixed to the outer surface of the bearing and is connected to the shaft.
According to this aspect, the driving force, which is inputted to the driven portion comprised of the pulley portion and the arm portion, rotates the impeller through the shaft, which is connected to the driven portion.